USC has often been an enigma the past two years, at times defying expectations under NCAA sanctions while also providing plenty of letdowns.

The Trojans won 10 games two of the past three seasons, but are viewed as a program rising from the turmoil of three coaches in 2013. National media frequently ask about losing Los Angeles to crosstown rival UCLA after two straight losses, but USC’s already got 15 commitments and a top 10 recruiting class.

With probation over and 18 starters back, new USC coach Steve Sarkisian is expected to enjoy a successful season. Or to put it another way, just avoid screwing things up like Lane Kiffin often did during his tenure.

After one week of training camp, Sarkisian’s biggest issues are the offensive line and secondary. USC looks like it will have three linemen start the season opener — Aug. 30 vs. Fresno State at the Coliseum — who never started a college game.

That should worry Sarkisian and quarterback Cody Kessler.

“We need eight really good guys that can rotate through for our season to be really successful,” Sarkisian said. “We would love the luxury of 10, but eight is good enough so that’s what we’re trying to get.”

Sarkisian won’t name starters, but Zach Banner is the top right tackle. One of the nation’s top 10 players two years ago, he might finally deliver on the hype.

“Zach’s done a good job,” offensive line coach Tim Drevno said. “He’s really in a zone (so far) but nothing’s been set.”

True freshman Toa Lobendahn will start at left guard as long as Aundrey Walker struggles coming back from a fractured ankle.

The biggest doubt is right guard, where redshirt freshman Khaliel Rodgers and true freshman Damien Mama get most of the snaps. Mama weighs 385 pounds, which makes even Drevno wonder if he can handle a lot of snaps in practice.

“Yeah, to be quite honest, for sure,” Drevno said.

If the linemen need to prove their talent, that is not the case at wide receiver. True freshmen Juju Smith and Adoree Jackson quickly emerged last week and are ready to play. Jackson is even more valuable at his first position of cornerback, especially because USC will have questions there too.

Defensive coordinator Justin Wilcox made it clear he wants Jackson at cornerback despite speculation he could move to offense.

“Of course!” Wilcox said.

Wilcox can count on cornerback Josh Shaw and safety Su’a Cravens, but doubts remain at the other spots. Kevon Seymour was a star of the Las Vegas Bowl against Fresno State, but struggled mightily against UCLA the previous game. Safety Leon McQuay is athletic but unproven, and if Smith were not so good at receiver he would challenge to start here. Jackson could start at cornerback or nickelback and seems destined to get on the field early.

“I’m trying to find a flaw right now with the guy,” Sarkisian said of the former Serra High star. “But he’s prepared, he studies, he gets his rest, he recovers, he comes energized and, ultimately, he knows what he’s doing and he’s making plays.”

USC fans often ask if quarterback Max Browne can overtake starter Cody Kessler. The answer through Week 1 is clearly no. Browne threw four interceptions over three practices to end the week and looks like he will need to hold off freshman Jalen Greene, who has a stronger arm but is even more inexperienced.

“You have to push them in drills to learn where they are,” Sarkisian said.

That is the question about USC overall. When will they get pushed? Against Stanford on Sept. 6?

The first six opponents all had winning records last season. so answers should come quickly.